Blood pressure is one of the most important vital signs your body produces. It is the force that blood exerts on the walls of your arteries as your heart pumps, and it directly affects your risk of heart disease, stroke, kidney disease, and cognitive decline. Nearly half of American adults have high blood pressure, and many do not know it because the condition typically causes no symptoms until serious damage has already occurred.
A blood pressure reading consists of two numbers expressed as a ratio, such as 120/80 mmHg. The top number is your systolic pressure — the peak force when your heart contracts and pushes blood into the arteries. The bottom number is your diastolic pressure — the baseline force between beats when your heart relaxes. Both are measured in millimeters of mercury (mmHg), a unit dating back to the original mercury column devices used to measure pressure.
| Category | Systolic (mmHg) | Diastolic (mmHg) | Action |
|---|---|---|---|
| Normal | Less than 120 | Less than 80 | Maintain healthy habits |
| Elevated | 120–129 | Less than 80 | Lifestyle changes |
| Stage 1 Hypertension | 130–139 | 80–89 | Lifestyle + possible medication |
| Stage 2 Hypertension | 140 or higher | 90 or higher | Lifestyle + medication |
| Hypertensive Crisis | Higher than 180 | Higher than 120 | Call 911 immediately |
Categories per 2017 ACC/AHA Guideline for High Blood Pressure in Adults.
Use the Blood Pressure Calculator to classify your readings and track changes over time.
Hypertension is called the “silent killer” because it rarely produces noticeable symptoms. Over months and years, elevated pressure damages artery walls, making them stiffer and more prone to plaque buildup. This increases the risk of heart attack, stroke, heart failure, kidney disease, vision loss, and vascular dementia. The relationship between blood pressure and cardiovascular risk is continuous — every 20 mmHg increase in systolic pressure doubles the risk of a fatal cardiac event.
Use a validated upper-arm monitor. Wrist monitors and finger devices are less accurate. The American Heart Association recommends monitors that have been validated against clinical-grade equipment.
Prepare before measuring. Sit quietly for 5 minutes before taking a reading. Avoid caffeine, exercise, and smoking for at least 30 minutes before measurement. Empty your bladder first, as a full bladder can raise readings by 10 to 15 mmHg.
Position matters. Sit with your back supported, feet flat on the floor, and arm resting at heart level on a table. Crossing your legs can raise systolic pressure by 2 to 8 mmHg. Rolling up a tight sleeve can constrict the arm and produce artificially high readings.
Take multiple readings. Measure twice in the morning and twice in the evening for seven consecutive days. Discard the first day’s readings (they tend to be higher due to anxiety) and average the remaining values. This gives a much more reliable picture than a single office reading.
White Coat Hypertension: Up to 30% of people show elevated blood pressure in a doctor’s office but normal readings at home. This is called white coat hypertension and is caused by the anxiety of a medical setting. Home monitoring helps distinguish true hypertension from this artifact.
Reduce sodium intake. The average American consumes about 3,400 mg of sodium daily. Reducing this to 1,500 mg can lower systolic pressure by 5 to 6 mmHg. Most dietary sodium comes from processed and restaurant foods, not the salt shaker — reading nutrition labels is essential.
Increase potassium intake. Potassium helps your kidneys excrete sodium and relaxes blood vessel walls. Aim for 3,500 to 5,000 mg daily from foods like bananas, potatoes, spinach, beans, and yogurt. Supplementation should only be done under medical supervision, especially for people with kidney disease.
Exercise regularly. 150 minutes per week of moderate aerobic activity (brisk walking, cycling, swimming) can lower systolic pressure by 5 to 8 mmHg. The effect is comparable to many first-line medications. Resistance training also helps but should be combined with aerobic exercise rather than replacing it.
Maintain a healthy weight. Blood pressure rises with body weight. Losing even 5 to 10 pounds can produce measurable reductions. For every kilogram of weight lost, systolic pressure drops by approximately 1 mmHg.
Limit alcohol. More than one drink per day for women or two for men is associated with higher blood pressure. Reducing consumption or eliminating alcohol entirely can lower systolic pressure by 2 to 4 mmHg.
Manage stress. Chronic stress contributes to sustained blood pressure elevation through hormonal pathways. Techniques with the strongest research support include regular physical activity, adequate sleep (7 to 9 hours), mindfulness meditation, and maintaining social connections.
Lifestyle changes are the first line of treatment, but medication is recommended when blood pressure remains at or above 130/80 with additional cardiovascular risk factors, or at 140/90 regardless of other risk. Common medication classes include ACE inhibitors, ARBs, calcium channel blockers, and thiazide diuretics. Most people with Stage 2 hypertension need two or more medications to reach target levels. Always work with your healthcare provider to determine the right treatment plan.
Try it now. Use the free Blood Pressure Calculator to classify your readings and understand what your numbers mean — no signup required.
Related tools: Blood Pressure Calculator · BMI Calculator · Heart Rate Calculator · Calorie Calculator